Studies on the Effects of the Removal of the Frontal Ganglion in Locusta Migratoria L

Abstract

1. A cytochemical investigation was made of the RNA content of the cells of the mid-gut, fat body and epidermis in third- and fourth-instar Locusta migratoria L. from which the frontal ganglion had been removed, in control operated and in starved animals. In operated locusts the nucleus was smaller, the nucleoli small or absent, and the cytoplasmic RNA much less than that found in operated controls. No differences were observed in the DNA content of the cells. 2. Autoradiograph studies were made of the uptake of 3H-uridine into the cells of operated and control operated locusts. In operated locusts the appearance of labelled uridine in the nucleus was delayed, the rate of uptake slower, and the total amount incorporated less (never more than 25%) than in the controls. 3. Studies were made of the uptake of 14C-uridine into the nuclei of operated and control-operated locusts. Nuclei were isolated from locusts killed at known times after the isotope had been injected and their radioactivity was measured. The results confirmed those found in the radioautographic studies. 4. The significance of these results is considered in the light of the Jacob & Monod model of the control of protein synthesis.